Handling negative timesteps

[paulrossmanith]

Hello there!

First of all, thank you for providing such an amazing toolbox, I really appreciate the time and effort spent! It helped me out tremendously!
However, when using e.g. madgwick.Dt to set the filters sampling time, negative values are also accepted. It should at least spew a warning to save some time debugging. :)

Cheers!

[Mayitzin]

Good idea. Although the prevention of error from the user input won't be high up in the priorities. Perhaps for the next release I can help with that.